1. Field of the Invention
The present invention relates to erasing a disk of a hard disk drive.
2. Background Information
Hard disk drives contain a plurality of magnetic heads that are coupled to rotating disks. The heads write and read information by magnetizing and sensing the magnetic fields of the disk surfaces. The heads are mounted to an actuator arm assembly that has a voice coil motor. The voice coil motor can move the heads across the surfaces of the disks. The disks typically have embedded servo information that is used to control the position of the heads. The disks are spun by a spindle motor that is mounted to a base plate of the disk drive.
For various reasons it is necessary to bulk erase the entire surfaces of the disks. Bulk erasing includes erasure of both data and servo. It is desirable to erase the magnetic disk without removing the disk from the disk drive assembly. Having to remove the disks significantly increases the time required to bulk erase the drive.
The disks can be bulk erased with the write heads of the disk drive but this requires movement of the heads along the entire disk surfaces. Another approach is to place the disks adjacent to a powerful erasure head that can erase a large area of the disk surfaces. The spindle motor spins the disks so that the entire disk surfaces are exposed to the magnetic field of the erasure head. The strong magnetic field of the erasure head can become coupled to the spindle motor and create a counteractive Lorentz force that slows down, and possibly stops, the spindle motor. The current to the spindle motor must be increased to overcome the drag of the Lorentz force created by the erasure head. High currents can potentially damage the spindle motor.